SA1100/PXA RTC clean-up
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Cover letter [PATCH v4 0/6] SA1100/PXA RTC clean-up
Quoted 38 lines · Robert Jarzmik
Quoted 9 lines · Rob Herring
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- you explain in the commit message that from a userland perspective, nothing changes, except that the RTC IP will change, and any dependency on a
The IP does not change here. rtc0 is still going to be the SA1100 RTC being registered first. The only change will be the addition of rtc1.
For boards which were only using
rtc-pxa.c(as mioa701 for example), they relied on the fact that rtc0 ==pxa_rtc. Their time is stored in PXA IP. Therefore, each of their hwclock will end up on sa1100-rtc instead of pxa-rtc.Quoted 7 lines
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So for these boards, ie. for all boards where only
rtc-pxa.cwas used, the IP addressed changes from a casual userspace perspective.Okay, so this is the case where the time will be wrong.
I could remove the select of the sa1100-rtc and do an empty function for
sa1100_rtc_init. This would preserve current behavior.Please don't. I only ask for a sentence in the commit message.
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bootloader fidling with RTC should be considered as a source of regression.
I'm not sure that I follow.
Let's talk about how a double boot windows + linux box works. The bootloader ensures that :
- sa1100-rtc holds the number of seconds since the OS start (think jiffies)
- pxa-rtc holds the wall clock timeUpon each reboot, sa1100-rtc is checked to see how much time has passed. If an "oustanding number" is detected, for example 10 years, the firmware resets the data partition.
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Now think what will happen when this change will be commited, upon the first reboot after the linux kernel has change sa1100-rtc time.
That would be bad. But on these platforms, the kernel has been using both RTCs right? Presumably on platforms only using 1 of the RTCs, the bootloader does not touch the RTCs.
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No, the kernel has been using only pxa-rtc. The sa1100-rtc is not used, and yet it accounts the passed time in it.
On platforms where all the OSes use only 1 RTC, the bootloader only touches one RTC, that's correct. Or said differently : the bootloader touches the union of all the RTCs the OSes it launches do touch.
Sorry, I'm being dense here, but I'm not any less confused as to which scenarios you think have an issue. Rather than go around again on this, perhaps you can just provide the warning for the commit text. Here's what I have.
Rob
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From
e43db14b27486faef8d8e74e4aa555aba7f31a0eMon Sep 17 00:00:00 2001
From: Rob Herring <[email protected]>
Date: Mon, 1 Jun 2015 07:53:01 -0500
Subject: [PATCH] ARM: config: Switch PXA27x platforms to use PXA RTC driver
With the SA1100 and PXA RTC drivers be mutually exclusive and no longer sharing hardware, PXA27x/PXA3xx platforms must use the PXA RTC driver as the SA1100 platform device is no longer registered.
This change should be transparent to userspace, but the first reboot after the switch will have the wrong time.
--- arch/arm/configs/cm_x2xx_defconfig | 2 +- arch/arm/configs/em_x270_defconfig | 2 +- arch/arm/configs/magician_defconfig | 2 +- arch/arm/configs/palmz72_defconfig | 2 +- arch/arm/configs/pcm027_defconfig | 2 +- arch/arm/configs/trizeps4_defconfig | 2 +- 6 files changed, 6 insertions(+), 6 deletions(-)
arch/arm/configs/cm_x2xx_defconfig +1 -1
@@ -157,7 +157,7 @@ CONFIG_LEDS_TRIGGERS=y CONFIG_LEDS_TRIGGER_HEARTBEAT=y CONFIG_RTC_CLASS=y CONFIG_RTC_DRV_V3020=y -CONFIG_RTC_DRV_SA1100=y +CONFIG_RTC_DRV_PXA=y CONFIG_EXT2_FS=y CONFIG_EXT3_FS=y CONFIG_INOTIFY=y
arch/arm/configs/em_x270_defconfig +1 -1
@@ -157,7 +157,7 @@ CONFIG_LEDS_TRIGGERS=y CONFIG_LEDS_TRIGGER_HEARTBEAT=y CONFIG_RTC_CLASS=y CONFIG_RTC_DRV_V3020=y -CONFIG_RTC_DRV_SA1100=y +CONFIG_RTC_DRV_PXA=y CONFIG_EXT2_FS=y CONFIG_EXT3_FS=y CONFIG_INOTIFY=y
arch/arm/configs/magician_defconfig +1 -1
@@ -150,7 +150,7 @@ CONFIG_LEDS_TRIGGERS=y CONFIG_LEDS_TRIGGER_BACKLIGHT=y CONFIG_RTC_CLASS=y CONFIG_RTC_DEBUG=y -CONFIG_RTC_DRV_SA1100=y +CONFIG_RTC_DRV_PXA=y CONFIG_EXT2_FS=y CONFIG_INOTIFY=y CONFIG_MSDOS_FS=m
arch/arm/configs/palmz72_defconfig +1 -1
@@ -67,7 +67,7 @@ CONFIG_MMC=y CONFIG_MMC_DEBUG=y CONFIG_MMC_PXA=y CONFIG_RTC_CLASS=y -CONFIG_RTC_DRV_SA1100=y +CONFIG_RTC_DRV_PXA=y CONFIG_EXT2_FS=y CONFIG_EXT3_FS=y # CONFIG_DNOTIFY is not set
arch/arm/configs/pcm027_defconfig +1 -1
@@ -82,7 +82,7 @@ CONFIG_MMC=y CONFIG_MMC_PXA=y CONFIG_RTC_CLASS=y CONFIG_RTC_DRV_PCF8563=m -CONFIG_RTC_DRV_SA1100=m +CONFIG_RTC_DRV_PXA=m CONFIG_EXT2_FS=m CONFIG_EXT3_FS=m # CONFIG_DNOTIFY is not set
arch/arm/configs/trizeps4_defconfig +1 -1
@@ -177,7 +177,7 @@ CONFIG_NEW_LEDS=y CONFIG_RTC_CLASS=y # CONFIG_RTC_HCTOSYS is not set CONFIG_RTC_DRV_PCF8583=m -CONFIG_RTC_DRV_SA1100=y +CONFIG_RTC_DRV_PXA=y CONFIG_EXT2_FS=y CONFIG_EXT2_FS_XATTR=y CONFIG_EXT2_FS_POSIX_ACL=y
Signature · 1 line
2.1.0